Conventionally, there is known a hybrid vehicle equipped with an automatic transmission having a first input shaft which is selectively coupled to an output shaft via a plurality of gear trains establishing gear shift stages, and which is connected to an electric motor, a second input shaft which is selectively coupled to the output shaft via a plurality of gear trains establishing variable speed stages, a first clutch capable of switching between a transmission state of transmitting a driving force of an internal combustion engine to the first input shaft and an opened state which cuts off the transmission, and a second clutch capable of switching between the transmission state of transmitting the driving force of the internal combustion engine to the second input shaft and the opened state which cuts off the transmission (for example, refer to Patent Document 1 and 2). In the automatic transmission, it is possible to start up the internal combustion engine by the driving force of the electric motor.
Recently, for improvement of fuel consumption and environmental performance, it is proposed to perform an idling stop control of automatically stopping the internal combustion engine during vehicle stop.
In Patent Document 2, there is disclosed that the starting up of the internal combustion engine is permitted, during an EV travel only with the driving force of the electric motor (motor), in the case where a vehicle speed is equal to or more than a determination vehicle speed. Further, in Patent Document 2, there is disclosed that during vehicle stop, it is switched from EV start to a start by the driving force of the internal combustion engine, in the case where an estimated electric storage state of an electric storage device (battery) drops below a preliminary set determination value, or in the case where an estimated road surface inclination exceeds a preliminary set determination inclination.